What Is the Ring of Light Around the Moon When There Is a Solar Eclipse? | The Classroom | Synonym What Is the Ring of Light Around the Moon When There Is a Solar Eclipse? by Tammie Painter The ring around the moon in a total eclipse is caused by the sun's corona. Related Articles Does the Moon Have Solar Wind Storms? If you're at the right place at the right time, you might witness a total solar eclipse. During this dramatic event, the moon blocks out the light of the sun to observers on Earth. As the moon covers the sun, rings of light appear from the corona, which appears at the edge of the sun's disk. Careful observers will be able to see the changes in this light during the course of the eclipse. The Corona At totality, a crown of glowing light shines around the moon. This light comes from the sun's outermost region, its corona. Occasionally, red areas of light dot the corona. This event is hydrogen gas, as it travels along loops of the sun's magnetic field caused by the activity of sunspots. First and Second Contact A total eclipse occurs when the moon is in exact alignment between the sun and the earth.

During first contact, the moon moves in front of the sun, and the sun changes from a bright, round orb to a crescent. At second contact, the moon covers the sun, and a faint strip of sunlight is visible at the edge of the moon. This strip is caused by the many craters, valleys and mountains that give the moon a rough surface. This strip of light also appears at third contact, when the moon begins to move out of the path of the sun. Baily's Beads Following second contact, bright beads of light appear at the edge of the moon. Called Baily's beads, these dots of lights, like the light strip seen in second contact, are caused by the sun's light peeking through the moon's rough surface. Baily's beads occur at only one edge of the moon; the glow of the sun's corona. appears at the other edge. Diamond Ring & Chromosphere Just before totality, some of the sun's light still peeks past the moon, while the sun's corona begins to form more fully around the moon. At this point, a bright spot of light appears at one edge of the moon.

With a thin corona band and the moon's dark circle, it looks like a diamond ring hanging in the sky. Just after the diamond ring appears, watch for a thin strip of red light around the moon. This is the sun's chromosphere. Ring of Fire In a total eclipse, the moon totally covers the surface of the sun. When the moon is at its farthest point from Earth, it can pass in front of the sun but not cover the sun entirely. This event is called an annular eclipse. At the peak of an annular eclipse, a ring of sunlight is still visible behind the moon. The ring glows red, yellow and orange, giving it the name Ring of Fire. References Rings Around The Moon Moon Rings, Moon Dogs And Other Moon Light Phenomena... The moon can produce interesting optical effects when conditions are right. The most common of which are moon rings, moon bows, which are similar to rainbows, moon dogs and moon pillars. A rainbow is produced when sunlight is refracted through water droplets - A similar effect is produced when moon light refracts through ice crystals. Below are a few photographs and examples about this interesting phenomena. Thanks to everyone that helped me put together this simple explanation of moon light effects.

A Ring Around The Moon The ring around the Moon is caused by the refraction of Moonlight (which of course is reflected sunlight) from ice crystals in the upper atmosphere. The shape of the ice crystals results in a focusing of the light into a ring. Since the ice crystals typically have the same shape, namely a hexagonal shape, the Moon ring is almost always the same size. Less typical are the halos that may be produced by different angles in the crystals. They can create halos with an angle of 46 degrees. Moon Ring Weather Folklore Folklore has it that a ring around the moon signifies bad weather is coming, and in many cases this may be true. So how can rings around the moon be a predictor of weather to come? The ice crystals that cover the halo signify high altitude, thin cirrus clouds that normally precede a warm front by one or two days. Typically, a warm front will be associated with a low pressure system which is commonly referred to as a storm. It is believed that the number of stars within a moon halo indicate the number days before bad weather will arrive. Give it a try the next time you observe a moon halo.

Rings Around The Sun - The same phenomena that causes lunar halos can also be observed around the sun. A few photos of solar halos using a Coolpix 995 digital camera. NOTICE: Never look at or photograph the sun directly. Anatomy of a Moon Halo The ring that appears around the moon arises from light passing through six-sided ice crystals high in the atmosphere. These ice crystals refract, or bend, light in the same manner that a camera lens bends light. The ring has a diameter of 22� , and sometimes, if you are lucky, it is also possible to detect a second ring, 44� diameter. Thin high cirrus clouds lofting at 20,000 feet or more contain tiny ice crystals that originate from the freezing of super cooled water droplets. These crystals behave like jewels refracting and reflecting in different directions. Cloud crystals are varieties of hexagonal prisms, (6 sides) and range in shapes from long columns to thin plate-like shapes that have different face sizes. Moon Dogs Moon dogs are the paler version of sun dogs: bursts of light often in reds and blues that appear on both sides of the moon.

Both phenomena are the work of almost invisible clouds that reside in the atmosphere where commercial airliners cruise, at about 30,000 feet. The clouds are composed largely of ice crystals, known as diamond dust. The official name for a moon dog is a paraselene if seen at 22 degrees. If the image is at 90, 120 or 140 degrees then it's known as a parantiselene. Thanks to Jim Bell for the moon dog photo !!! Visit Jim's Homepage for more great photographs. Moon Corona Another interesting effect caused by moon light is the corona. Just like lunar halos, coronas are produced by high thin clouds. But unlike halos coronas are very small in size. Thanks to Mats Mattsson for the moon corona photo !!! Visit Mats Homepage for more great photographs. AUSTRALIA Moon Corona A typical corona is only couple degrees in diameter and closely fringes the moon. Although not as intense as a solar rainbow, coronas may appear in several colors. On rare occasions lunar halos and lunar coronas can appear together. This great photo of a moon corona was captured by Robert Studdert of Hurtsville Australia.

Christian Halo Christian Halo Nimbus General Information In Christian sacred art (Eastern and Western churches), holy persons (saints) are depicted with a halo, a golden, yellow or white circular glow, around the head. It is sometimes called a nimbus as well. The halo appears in the art of ancient Greece and Rome, and was incorporated into Christian art sometime in the 4th century. Round halos are used to signify saints. A cross within a halo is used to represent Jesus Christ. Triangular halos are used for representations of the Trinity. Square halo are used to depict unusually saintly living personages. In popular piety, this practice has led to the belief that saints during their earthly life actually walked around with a halo around their head. Of the many wonderful stories about saints, some report that a saint was literally glowing. This is called the aureole, a lemon-drop-shaped item that appears to radiate from the entire body of the holy being. Finally, there is also "glory," a glowing effusion used to cover up depictions of genitalia. Text Font Face E-mail The halo underwent an interesting transformation during the Renaissance. Originally, the halo represented a glow of sanctity emanating from the head.

Since it was conventionally drawn as a circle, during the Renaissance, when perspective became more important in art, the halo was changed from an aura surrounding the head to a golden ring that appeared in perspective, mysteriously floating above the heads of the saints. Halo General Information The Halo, also called Nimbus, in art, is a radiant circle or disk surrounding the head of a holy person, a representation of spiritual character through the symbolism of light. In Hellenistic and Roman art the sun-god Helios and Roman emperors often appear with a crown of rays. Because of its pagan origin, the form was avoided in Early Christian art, but a simple circular nimbus was adopted by Christian emperors for their official portraits. From the middle of the 4th century, Christ was also shown with this imperial attribute, as was his symbol, the Lamb of God, from the end of the 4th century. In the 5th century it was sometimes given to angels, but it was not until the 6th century that the halo became customary for the Virgin Mary and other saints. For a period during the 5th century, living persons of eminence were depicted with a square nimbus.

The halo was used regularly in representations of Christ, the angels, and the saints throughout the Middle Ages. Often Christ's halo is quartered by the lines of a cross or inscribed with three bands, interpreted to signify his position in the Trinity. From the 15th century, however, with the growth of naturalism in Renaissance art, the nimbus created problems in representation. At first it was treated by some Florentine artists as a solid object seen in perspective, a disk fixed to the back of a saint's head. The inadequacy of this solution led to its decline in Italian art in the 16th century and to its abandonment by Michelangelo and Titian. In Flemish painting of the 15th century, it began to be represented as rays of light; under the influence of the Counter-Reformation, which sought to restore a glorious conception to religious art, this form was adopted by Italian artists of the late 16th century, notably Tintoretto, as a realistically rendered light emanating from the holy person's head. This new interpretation was the standard one in the Baroque period and in most subsequent religious works.

The halo is also found in Buddhist art of India, appearing from the late 3rd century AD. It is believed that the motif was brought to the East by Greek invaders. Encyclopaedia Britannica Nimbus Advanced Information (Latin, related to Nebula, nephele, properly vapour, cloud), in art and archaeology signifies a shining light implying great dignity. Closely related are the halo, glory, and aureole. In Nature All such symbols originate in natural phenomena, scientifically accounted for in textbooks on physics. There are circular phenomena of light in drops or bubbles of water and in ice crystals which by the refraction of light reveal in greater or less degree the spectral colours. Of the accompanying phenomena the horizontal and vertical diameters, the "column of light", may be mentioned. The curious rings of light or colour similar to the above, which often form themselves before the iris of the eye even in candle light, are more gorgeous on the mountain mist (Pilatus, Rigi, and Brocken), if the beholder has the sun behind him; they surround his shadow as it is projected upon the clouds. The dewdrops in a meadow can produce an appearance of light around a shadow, without, however, forming distinct circles.

Occasionally one even sees the planet Venus veiled by a disc of light. The phenomena of discs and broad rings are more usual in the sun and moon. The Babylonians studied them diligently (Kugler, "Sternkunde und Sterndienst in Babel", II, 1). The terminology of these phenomena is vague. The disc or circle around the sun can be correctly called "anthelia", and the ring around the moon "halo". A more usual name is "aureole", which in a restricted sense means an oval or elliptical ray of light like a medallion. If the brightness is merely a luminous glow without definitely forming ring, circle. or ellipse, it is usually spoken of as a "glory". The types in nature in which rays or beams of light with or without colour challenge attention, suggested the symbolical use of the nimbus to denote high dignity or power. It is thus that Divine characteristics and the loftiest types of humanity were denoted by the nimbus. In Poetry In poetry, this symbol of light is chiefly used in the form of rays and flames or a diffused glow. The Bible presents the best example: God is Light.

The Son of God, the Brightness of His Father's glory (Hebr., i, 3). An emerald light surrounds God and His throne (Apoc., iv, 3), and the Son of Man seems to the prophet a flame of fire (Apoc., i, 14 sq.). So also He appeared in His Transfiguration on Tabor. On Sinai, God appeared in a cloud which at once concealed and revealed Him (Ex., xxiv, 16, sq.) and even the countenance of Moses shone with a marvellous light in the presence of God (Ex., xxxiv, 29, sq.). Such descriptions may have influenced Christian artists to distinguish God and the saints by means of a halo, especially around the head. They were also familiar with the descriptions of the classical poets whose gods appeared veiled by a cloud; e. g. according to Virgil, divinity appears "nimbo circumdata, succincta, effulgens" (bathed in light and shining through a cloud). In Art In the plastic arts (painting and sculpture) the symbolism of the nimbus was early in use among the pagans who determined its form.

In the monuments of Hellenic and Roman art, the heads of the gods, heroes, and other distinguished persons are often found with a disc-shaped halo, a circle of light, or a rayed-fillet. They are, therefore, associated especially with gods and creatures of light such as the Phoenix. The disc of light is likewise used in the Pompeian wall paintings to typify gods and demigods only, but later, in profane art it was extended to cherubs or even simple personifications, and is simply a reminder that the figures so depicted are not human. In the miniatures of the oldest Virgil manuscript all the great personages wear a nimbus. The custom of the Egyptian and Syrian kings of having themselves represented with a rayed crown to indicate the status of demigods, spread throughout the East and the West. In Rome the halo was first used only for deceased emperors as a sign of celestial bliss, but afterwards living rulers also were given the rayed crown, and after the third century, although not first by Constantine, the simple rayed nimbus. Under Constantine the rayed crown appears only in exceptional cases on the coin, and was first adopted emblematically by Julian the Apostate.

Henceforth the nimbus appears without rays, as the emperors now wished themselves considered worthy of great honour, but no longer as divine beings. In early Christian art, the rayed nimbus as well as the rayless disc were adopted in accordance with tradition. The sun and the Phoenix received, as in pagan art, a wreath or a rayed crown, also the simple halo. The latter was reserved not only for emperors but for men of genius and personifications of all kinds, although both in ecclesiastical and profane art, this emblem was usually omitted in ideal figures. In other cases the influence of ancient art tradition must not be denied. The Middle Ages scarcely recognized such influence, and were satisfied to refer to the Bible as an example for wreath and crown or shield shaped discs as marks of honour to holy personages. Durandus writes: "Sic omnes sancti pinguntur coronati, quasi dicerunt. Filiae Jerusalem, venite et videte martyres cum coronis quibus coronavit eas Dominus. Et in Libro Sapientiae: Justi accipient regnum decoris et diadema speciei de manu Domini.

Corona autem huiusmodi depingitur in forma scuti rotundi, quia sancti Dei protectione divina fruuntur, unde cantant gratulabundi: Domine ut scuto bonae voluntatis tuae coronasti nos" (Thus all the saints are depicted, crowned as if they would say: O Daughters of Jerusalem, come and see the martyrs with the crowns with which the Lord has crowned them. And in the Book of Wisdom: The Just shall receive a kingdom of glory, and a crown of beauty at the hands of the Lord, and a crown of this kind is shown in the form of a round shield. because they enjoy the divine protection of the Holy God, whence they sing rejoicing: O Lord, Thou hast crowned us with a shield of Thy goods-will.) (Rationale divin. offic., I, 3, 19, sq.). Furthermore the Middle Ages are almost exclusively accredited with the extension of symbolism inasmuch as they traced, sometimes felicitously, allusions to Christian truths in existing symbols, of which they sought no other origin.

Durandus adds to the passage quoted above, the nimbus containing a cross, usual in the figures of Christ, signifying redemption through the Cross, and the square nimbus which was occasionally combined with it in living persons, to typify the four cardinal virtues. Judging by the principal monuments, however, the square nimbus appears to be only a variant of the round halo used to preserve a distinction and thus guard against placing living persons on a par with the saints. The idea of the cardinal virtues, the firmness of a squared stone, or the imperfection of a square figure as contrasted with a round one was merely a later development. In the cross nimbus the association of the nimbus with an annexed cross must be conceded historical; but that this cross is a "signum Christi crucifixi" Durandus probably interprets correctly. Origin As stated above the nimbus was in use long before the Christian era. According to the exhaustive researches of Stephani it was an invention of the Hellenic epoch.

In early Christian art the nimbus certainly is not found on images of God and celestial beings, but only on figures borrowed from profane art, and in Biblical scenes; in place of the simple nimbus, rays or an aureole (with the nimbus) were made to portray heavenly glory. Hence it follows that the Bible furnished no example for the bestowal of a halo upon individual saintly personages. As a matter of fact the nimbus, as an inheritance from ancient art tradition, was readily adopted and ultimately found the widest application because the symbol of light for all divine, saintly ideals is offered by nature and not infrequently used in Scripture. In contemporary pagan art, the nimbus as a symbol of divinity had become so indefinite, that it must have been accepted as something quite new. The nimbus of early Christian art manifests only in a few particular drawings, its relationship with that of late antiquity. In the first half of the fourth century, Christ received a nimbus only when portrayed seated upon a throne or in an exalted and princely character, but it had already been used since Constantine, in pictures of the emperors, and was emblematic, not so much of divine as of human dignity and greatness.

In other scenes however, Christ at that time was represented without this emblem. The "exaltation" of Christ as indicated by the nimbus, refers to His dignity as a teacher and king rather than to His Godhead. Before long the nimbus became a fixed symbol of Christ and later (in the fourth century), of an angel or a lamb when used as the type of Christ. The number of personages who were given a halo increased rapidly, until towards the end of the sixth century the use of symbols in the Christian Church became as general as it had formerly been in pagan art. Miniature painting in its cycle represents all the most important personages with haloes, just as did the Virgil codex, so that the continuity of the secular and Christian styles is obvious. This connection is definitively revealed when royal persons, e.g., Herod, receive a nimbus. Very soon the Blessed Virgin Mary always, and martyrs and saints usually, were crowned with a halo. More rarely the beloved dead or some person conspicuous for his position or dignity were so honoured. Saints were so represented if they constituted the central figure or needed to be distinguished from the surrounding personages.

The nimbus was used arbitrarily in personification, Gospel types, and the like. Official representations clearly show a fixed system, but outside of these there was great variety. Works of art may be distinctly differentiated according to their birthplace. The nimbus in the Orient seems to has e been in general use at an early period, but whether it was first adopted from ecclesiastical art is uncertain. In general the customs of the East and West are parallel; for instance, in the West the personifications appear with a nimbus as early as the third century and Christ enthroned no later than in the East (in the time of Constantine). Their nature makes it apparent that in every department of plastic art the nimbus is more rarely used than in painting. Form and Colour The form of the symbol was first definitely determined by Gregory the Great who (about 600) permitted himself to be painted with a square nimbus.

Johannus Diaconus in his life of the pope, gives the reason: "circa verticem tabulae similitudinem, quod viventis insigne est, preferens, non coronam" (bearing around his head the likeness of a square, which is the sign for a living person, and not a crown.) (Migne, "P.L.", 75, 231). It appears to have already been customary to use the round nimbus for saints. In any event the few extant examples from the following centuries show that, almost without exception only the living, principally ecclesiastics, but also the laity and even women and children, were represented with a square nimbus. The aureole, that is the halo which surrounds an entire figure, naturally takes the shape of an oval, though if it is used for a bust, it readily resumes the circular form. The radiation of light from a centre is essential and we must recognize the circle of light of the sun-god in ancient art as one of the prototypes of the aureole. The medallion form was for a long time in use among the ancient Romans for the Imagines clipeata.

The gradations of colour in the aureole reveal the influence of Apoc., iv, 3, where a rainbow was round about the throne of God. Indeed, in very early times the aureole was only used in representations of God as the Dove or Hand, or of Christ when the divinity was to be emphatically expressed. In early Christian times (as now) the round nimbus was by far the most usual designation of Christ and the saints. The broad circle is often replaced by the ring of light or a coloured disc, especially on fabrics and miniatures. In pictures without colour the nimbus is shown by an engraved line or a raised circlet, often by a disc in relief. In the aureole blue indicates celestial glory, and it is used in the nimbus to fill in the surface, as are yellow, gray, and other colours while the margins are sharply defined in different tints. In many haloes the inner part is white. In mosaics, since the fifth and sixth centuries, blue has been replaced by gold. From this period also, the frescoes show a corresponding yellow as seen for instance in paintings in the catacombs.

Gold or yellow prevails in miniatures, but there is a great deal of variety in illustrated books. Blue as a symbol of heaven has the preference, but gold, which later became the rule, gives a more obvious impression of light. The explanation of the cross nimbus variety is obvious. Since the sixth century it has characterized Christ and the Lamb of God, but occasionally it is given to the other Persons of the Trinity. In connection with it, in the fourth and fifth centuries there was a monogram nimbus. The cross and the monogram of Christ were beside or above the head of Christ and the Lamb. In the fifth century they were brought to the upper edge of the nimbus and finally both were concentrically combined with it. In more recent times the monogram and the monogram nimbus have become more rare. The letters Alpha and Omega for Christ and M and A for Mary, were intended for monograms and frequently accompanied the nimbus. Development In order to understand the nimbus and its history, it is necessary to trace it through the different branches of art. The frescoes in the catacombs have a peculiar significance inasmuch as they determine the period when the nimbus was admitted into Christian art.

The numerous figures lacking this symbol (Christ, Mary, and the Apostles) show that before Constantine, representations of specifically Christian character were not influenced by art traditions. Only pictures of the sun, the seasons, and a few ornamental heads carried a nimbus at that date. The single exception is found in a figure over the well-known "Ship in a Storm" of one of the Sacrament chapels. But it is to be observed that in this case we are not dealing with a representation of God, but merely with a personification of heavenly aid, which marked a transition from personifications to direct representations of holy personages. The figure seems to be copied from pictures of the sun god. On the other hand, several pictures of Christ in the catacombs, dating from the fourth century, indicate the period when the nimbus was first used in the way familiar to us. Besides the Roman catacombs others, especially that of El Baghaouat in the great Oasis of the Libyan desert, must be taken into account.

For the period succeeding Constantine, mosaics furnish important evidence since they present not only very numerous and usually definite examples of the nimbus, but have a more official character and give intelligent portrayals of religious axioms. Although allowance must be made for later restorations a constant development is apparent in this field. The treatment of the nimbus, in the illuminating and illustrating of books, was influenced by the caprices of the individual artist and the tradition of different schools. In textiles and embroidery the most extensive use was made of the nimbus, and a rich colour scheme was developed, to which these technical arts are by nature adapted. Unfortunately the examples which have been preserved are only imperfectly known and the dates are often difficult to determine. Sculpture presents little opportunity for the use of the nimbus. In some few instances, indeed, the nimbus is painted on ivory or wood carvings but more often we find it engraved or raised in relief. Figures with this emblem are rare. On the sarcophagi we find that Christ and the Lamb (apart from the sun) alone appear with a circle or disc, the Apostles and Mary, never. In ivory neither Mary nor Christ is so distinguished.

In the course of centuries the Christian idea that God, according to Holy Scripture the Source of Light and Divine things, must always be given a halo. became more pronounced. This applied to the three Divine Persons and their emblems, as the Cross, Lamb, Dove, Eye, and Hand; and since, according to Scripture, saints are children of Light (Luke, xvi, 8; John, xii, 36), as such they should share the honour. Preference was shown for the garland or crown (corona et gloriae corona) of Christ which was also bestowed by God as a reward upon the saints, either spiritually in this life or in the Kingdom of Heaven (Ps. xx, 4; Heb., ii, 7 sq.). Garlands and crowns of glory are frequently mentioned in the Bible (I Peter v, 4; Apoc., iv, 4, etc.). The nimbus also takes the form of a shield to emphasize the idea of Divine protection (Ps. v, 13).

A truly classic authority for the explanation of the nimbus may be found in Wis., v, 17: the Just shall "receive a kingdom of glory, and a crown of beauty at the hands of the Lord: for with His right hand He will cover them, and with His holy arm He will defend them." (In Greek, "Holds the shield over them".) Whereas in pagan art, the rayless nimbus signified neither holiness nor Divine protection but merely majesty and power, in Christian art it was more and more definitely made the emblem of such virtue and grace, which emanating from God, extends over the saints only. Urban VIII formally prohibited giving the nimbus to persons who were not beatified. Since the eighteenth century the word "halo" has been incorporated into the German language. In Western countries John the Baptist is the only saint of the Old Testament who is given a halo, doubtless because before his time the grace of Christ had not yet been bestowed in its fullness. We have already found that the aureole was be considered exclusively a device of Christian art, especially as it was reserved at first for the Divinity, and later extended only to the Blessed Virgin.

Instead of simple beams it often consists of pointed flames or is shaded off into the colours of the rainbow. This form as well as the simple nimbus, by the omission of the circumference, may be transposed into a garland of rays or a glory. A glory imitating the sun's rays was very popular for the monstrances, in other respects the lunula suggests the nimbus only because the costliness of the material enhances the lustre. The aureole obtained the Italian name of mandorla from its almond shape. In Germany the fish was agreed upon for the symbol of Christ, or a fish bladder if it had the shape of a figure 8. God the Father is typified in later pictures by an equilateral triangle, or two interlaced triangles, also by a hexagon to suggest the Trinity. If there is no circle around the cross nimbus, the three visible arms of the cross give the same effect. Occasionally the mandorla is found composed of seven doves (type of the Seven Gifts of the Holy Ghost), or of angels. The latter are used in large pictures of the Last Judgment or heaven, for instance in the "glories" of Italian domes.

In painting, haloes of cloud are sometimes used for delicate angel heads, as in Raphael's works. Angels also form a nimbus around the head of the Mother of God. She is also given the twelve stars of Apoc., xii, 1. Saint John Nepomucene has five or seven stars because of the great light which hovered over his body when he was drowned in the Moldau by order of King Wenceslaus. Artists have developed many varieties of the nimbus and aureole. Since the Renaissance it has been fashioned more and more lightly and delicately and sometimes entirely omitted, as the artists thought they could suggest the characteristics of the personage by the painting. It is true that the nimbus is not intrinsically a part of the figure and at times even appears heavy and intrusive. A distinguishing symbol may not, however, be readily dispensed with and with the omission of this one the images of the saints have often degenerated into mere genre pictures and worldly types.

A delicate circlet of light shining or floating over the head does not lessen the artistic impression, and even if the character of Christ or the Madonna is sufficiently indicated in the drawing, yet it must be conceded that the nimbus, like a crown, not only characterizes and differentiates a figure but distinguishes and exalts it as well. G Gietmann Transcribed by Michael C. Tinkler The Catholic Encyclopedia, Volume XI Nihil Obstat, February 1, 1911. Remy Lafort, S.T.D., Censor Imprimatur. +John Cardinal Farley, Archbishop of New York The individual articles presented here were generally first published in the early 1980s. This subject presentation was first placed on the Internet in December 1997. This page - - Solar Eclipse: What is a Total Solar Eclipse & When is the Next One? See photos of the 2016 total solar eclipse The next one will be an annular solar eclipse (also known as a "ring of fire" solar eclipse) on Sept. 1, 2016.

The total solar eclipse of 2016 reaches totality in this still image from a NASA webcast on March 8, 2016 from Woleai Island in Micronesia, where it was March 9 local time during the eclipse. Credit: NASA TV A solar eclipse occurs when the moon gets between Earth and the sun, and the moon casts a shadow over Earth. A solar eclipse can only take place at the phase of new moon, when the moon passes directly between the sun and Earth and its shadows fall upon Earth’s surface. But whether the alignment produces a total solar eclipse, a partial solar eclipse or an annular solar eclipse depends on several factors, all explained below. The fact that an eclipse can occur at all is a fluke of celestial mechanics and time. Since the moon formed about 4.5 billion years ago , it has been gradually moving away from Earth (by about 1.6 inches, or 4 centimeters per year). Right now the moon is at the perfect distance to appear in our sky exactly the same size as the sun, and therefore block it out. But this is not always true. When is the next solar eclipse?

The next solar eclipse visible from North America will be a total eclipse on Aug. 21, 2017. It will sweep across the continental United States from Oregon to Georgia. How Solar Eclipses Work: When the moon covers up the sun, skywatchers delight in the opportunity to see a rare spectacle. See how solar eclipses occur in this Space.com infographic . Credit: Karl Tate, SPACE.com Contributor Types of solar eclipses There are four types of solar eclipses: total, annular, partial and hybrid. Here’s what causes each type: Total solar eclipses These are a happy accident of nature. The sun's 864,000-mile diameter is fully 400 times greater than that of our puny moon , which measures just about 2,160 miles. But the moon also happens to be about 400 times closer to Earth than the sun (the ratio varies as both orbits are elliptical), and as a result, when the orbital planes intersect and the distances align favorably, the new moon can appear to completely blot out the disk of the sun. On the average a total eclipse occurs somewhere on Earth about every 18 months.

There are actually two types of shadows: the umbra is that part of the shadow where all sunlight is blocked out. The umbra takes the shape of a dark, slender cone. It is surrounded by the penumbra, a lighter, funnel-shaped shadow from which sunlight is partially obscured. During a total solar eclipse, the moon casts its umbra upon Earth's surface; that shadow can sweep a third of the way around the planet in just a few hours. Those who are fortunate enough to be positioned in the direct path of the umbra will see the sun's disk diminish into a crescent as the moon's dark shadow rushes toward them across the landscape. During the brief period of totality, when the sun is completely covered, the beautiful corona — the tenuous outer atmosphere of the sun — is revealed. Totality may last as long as 7 minutes 31 seconds, though most total eclipses are usually much shorter. On Jan. 4, 2011, the moon passed in front of the sun in a partial solar eclipse - as seen from parts of Earth. Here, the joint Japanese-American Hinode satellite captured the same breathtaking event from space. The unique view created what's called an annular solar eclipse.

Credit: Hinode/XRT Partial solar eclipses A partial solar eclipse occurs when only the penumbra (the partial shadow) passes over you. In these cases, a part of the sun always remains in view during the eclipse. How much of the sun remains in view depends on the specific circumstances. Usually the penumbra gives just a glancing blow to our planet over the polar regions; in such cases, places far away from the poles but still within the zone of the penumbra might not see much more than a small scallop of the sun hidden by the moon. In a different scenario, those who are positioned within a couple of thousand miles of the path of a total eclipse will see a partial eclipse. The closer you are to the path of totality, the greater the solar obscuration. If, for instance, you are positioned just outside of the path of the total eclipse, you will see the sun wane to a narrow crescent, then thicken up again as the shadow passes by. Annular solar eclipses An annular eclipse, though a rare and amazing sight, is far different from a total one. The sky will darken ...

somewhat; a sort of weird “counterfeit twilight” since so much of the sun still shows. The annular eclipse is a subspecies of a partial eclipse, not total. The maximum duration for an annular eclipse is 12 minutes 30 seconds. However, an annular solar eclipse is similar to a total eclipse in that the moon appears to pass centrally across the sun. The difference is, the moon is too small to cover the disk of the sun completely. Because the moon circles Earth in an elliptical orbit, its distance from Earth can vary from 221,457 miles to 252,712 miles. But the dark shadow cone of the moon’s umbra can extend out for no longer than 235,700 miles; that’s less than the moon’s average distance from Earth . So if the moon is at some greater distance, the tip of the umbra does not reach Earth. During such an eclipse, the antumbra, a theoretical continuation of the umbra, reaches the ground, and anyone situated within it can look up past either side of the umbra and see an annulus, or “ring of fire” around the moon.

A good analogy is putting a penny atop a nickel, the penny being the moon, the nickel being the sun. Hybrid solar eclipses These are also called annular-total (“A-T”) eclipses. This special type of eclipse occurs when the moon’s distance is near its limit for the umbra to reach Earth. In most cases, an A-T eclipse starts as an annular eclipse because the tip of the umbra falls just short of making contact with Earth; then it becomes total, because the roundness of the planet reaches up and intercepts the shadow tip near the middle of the path, then finally it returns to annular toward the end of the path. Because the moon appears to pass directly in front of the sun, total, annular and hybrid eclipses are also called “central” eclipses to distinguish them from eclipses that are merely partial. Of all solar eclipses, about 28 percent are total; 35 percent are partial; 32 percent annular; and just 5 percent are hybrids. Predictions of solar eclipses Eclipses do not happen at every new moon, of course. This is because the moon’s orbit is tilted just over 5 degrees relative to Earth’s orbit around the sun.

For this reason, the moon’s shadow usually passes either above or below Earth, so a solar eclipse doesn’t occur. But as a rule, at least twice each year (and sometimes as many as five times in a year), a new moon will align itself in just such a way to eclipse the sun. That alignment point is called a node. Depending on how closely the new moon approaches a node will determine whether a particular eclipse is central or partial. And of course, the moon’s distance from the Earth — and to a lesser degree, Earth’s distance from the sun — will ultimately determine whether a central eclipse is total, annular or a hybrid. And these alignments don’t happen haphazardly, for after a specific interval of time, an eclipse will repeat itself or return. This interval is known as the Saros cycle and was known as far back as the days of the early Chaldean astronomers some 28 centuries ago. The word Saros means “repetition” and is equal to 18 years, 11⅓ days (or a day less or more depending on the number of leap years that have intervened).

After this interval, the relative positions of the sun and moon relative to a node are nearly the same as before. That third of a day in the interval causes the path of each eclipse of a series to be displaced in longitude a third of the way around Earth to the west with respect to its predecessor. For example, on March 29, 2006, a total eclipse swept across parts of western and northern Africa and then across southern Asia. One Saros later, on April 8, 2024, this eclipse will recur, except instead of Africa and Asia, it will track across northern Mexico, the central and eastern United States and the Maritime provinces of Canada. Solar eclipse safety You should never look directly at the sun, but there are ways to safely observe an eclipse. See how to safely observe a solar eclipse with this Space.com infographic . Credit: Karl Tate, SPACE.com Contributor As a solar eclipse approaches, the mainstream media often will provide a variety of warnings and advisories against looking at the sun with bare eyes, as blindness could ensue. This has given most people the idea that eclipses are dangerous. Not so! It’s the sun that is dangerous — all the time!

The sun constantly emits invisible infrared rays that can damage your eyes. Ordinarily, we have no reason to gaze at the sun. An eclipse gives us a reason, but we shouldn’t. There are safe ways, however . . . By far, the safest way to view a solar eclipse is to construct a “pinhole camera.” A pinhole or small opening is used to form an image of the sun on a screen placed about 3 feet (or about 1 meter) behind the opening. Binoculars or a small telescope mounted on a tripod can also be used to project a magnified image of the sun onto a white card. The farther away the card, the larger you can focus the image. Look for sunspots. Notice that the sun appears somewhat darker around its limb or edge. This method of solar viewing is safe so long as you remember not to look through the binoculars or telescope when they are pointed toward the sun; put another way, never look directly at the sun when any part of its blindingly bright surface is visible. A variation on the pinhole theme is the “pinhole mirror.” Cover a pocket-mirror with a piece of paper that has a ¼-inch hole punched in it.

Open a sun-facing window and place the covered mirror on the sunlit sill so it reflects a disk of light onto the far wall inside. The disk of light is an image of the sun’s face. The farther away from the wall is the better; the image will be only 1 inch across for every 9 feet (or 3 centimeters for every 3 meters) from the mirror. Modeling clay works well to hold the mirror in place. Experiment with different-sized holes in the paper. Again, a large hole makes the image bright, but fuzzy, and a small one makes it dim but sharp. Darken the room as much as possible. Be sure to try this out beforehand to make sure the mirror’s optical quality is good enough to project a clean, round image. Of course, don’t let anyone look at the sun in the mirror. If you’re around leafy trees, look at the shadow cast by them during the partial phases. What do you see? Is it worth a photograph? You will see scores of partially eclipsed suns projected through pinhole gaps between the leaves. This is caused by diffraction, a property of light.

According to Vince Huegele, an optical physicist at the NASA Marshall Space Flight Center, the light rays do not shoot straight by the rim of the gaps, or a pinhole, but bend around the edge. This wave effect creates a pattern of rings that resembles a bull's eye. Acceptable filters for unaided visual solar observations include aluminized Mylar. Some astronomy dealers carry Mylar filter material specially designed for solar observing. Also acceptable is shade 14 arc-welder’s glass, available for just a few dollars at welding supply shops. Of course, it is always a good idea to test your filters and/or observing techniques before eclipse day. Unacceptable filters include sunglasses, old color film negatives, black-and-white film that contains no silver, photographic neutral-density filters and polarizing filters. Although these materials have very low visible-light transmittance levels, they transmit an unacceptably high level of near-infrared radiation that can cause a thermal retinal burn. The fact that the sun appears dim, or that you feel no discomfort when looking at the sun through these types of filters, is no guarantee that your eyes are safe.

There is one time when you can safely look directly at the sun: during a total eclipse, when the sun's disk is entirely covered. During those few precious seconds or minutes, the magnificent corona shines forth in all its glory surrounding the darkened sun; a marvelous fringe of pearly white light. It differs in size, in tints and patterns from eclipse to eclipse. It is always faint and delicate, with a sheen like a pale aurora. It has a variable appearance. Sometimes it has a soft continuous look; at other times, long rays of it shoot out in three or four directions. It may stand out from the disk in filmy petals and streamers. But when the sun begins to again emerge into view, the corona quickly disappears and you’ll need to protect your eyes once again. This photo of the partial solar eclipse of Sept. 13, 2015, was snapped by astrophotographer K.J. Mulder from his home in South Africa. Credit: K.J. Mulder/ Worlds in Ink Eclipses in ancient history As best as we can determine, the earliest record of a solar eclipse occurred over four millennia ago.

In China, it was believed that the gradual blotting out of the sun was caused by a dragon who was attempting to devour the sun, and it was the duty of the court astronomers to shoot arrows, beat drums and raise whatever cacophony they could to frighten the dragon away. In the ancient Chinese classic Shujing (or Book of Documents) is the account of Hsi and Ho, two court astronomers who were caught completely unaware by a solar eclipse, having gotten drunk just before the event began. In the aftermath, Zhong Kang, the fourth emperor of the Xia dynasty ordered that Hsi and Ho be punished by having their heads chopped off. The eclipse in question was that of Oct. 22 in the year 2134 B.C. In the Bible, in the book of Amos 8:9, are the words, “I will cause the sun to go down at noon, and I will darken the Earth in the clear day.” Biblical scholars believe this is a reference to a celebrated eclipse observed at Nineveh in ancient Assyria on June 15, 763 B.C. An Assyrian tablet also attests to the event. A solar eclipse even stopped a war.

According to the historian Herodotus, there was a five-year war that raged between the Lydians and the Medes. As the war was about to move into its sixth year, a Greek sage, Thales of Miletus foretold to the Ionians that the time was soon approaching when day would turn to night. On May 17, 603 B.C. the sun faded away just as Thales had alluded that it would. So believing that it was a sign from above, the combatants called a truce, which was cemented by a double marriage, for, as Herodotus wrote: “Without some strong bond, there is little of security to be found in men’s covenants.” And giving new meaning to the term, “Scared to death,” is the timid emperor Louis of Bavaria, the son of Charlemagne, who witnessed an unusually long total eclipse of the sun on May 5, A.D. 840, which lasted for over five minutes. But no sooner had the sun begun to emerge back into view, Louis was so overwhelmed by what he had just seen that he died of fright!

Modern study of eclipses Astronomers have learned much by studying eclipses and by the 18th century, observations of solar eclipses were recognized as providing veritable treasure troves of astronomical information, though sometimes getting that information wasn’t easy. Samuel Williams, a professor at Harvard, led an expedition to Penobscot Bay, Maine, to observe the total solar eclipse of Oct. 27, 1780. As it turned out, this eclipse took place during the Revolutionary War, and Penobscot Bay lay behind enemy lines. Fortunately, the British granted the expedition safe passage, citing the interest of science above political differences. And yet in the end, it was all for naught. Williams apparently made a crucial error in his computations and inadvertently positioned his men at Islesboro — just outside the path of totality — likely finding this out with a heavy heart when the narrowing crescent of sunlight slid completely around the dark edge of the moon and then started to thicken! During a total solar eclipse, a few ruby-red spots may seem to hover around the jet-black disk of the moon. Those are solar prominences, tongues of incandescent hydrogen gas rising above the surface of the sun. During the total eclipse of Aug.

18, 1868, the French astronomer Pierre Janssen trained his spectroscope on the prominences and discovered a new chemical element. Two English astronomers, J. Norman Lockyer and Edward Frankland, later named it “ helium ,” from the Greek helios (the sun). The gas was not identified on Earth until 1895. And because sunlight is blocked during a total eclipse, some of the brighter stars and planets can be observed in the darkened sky. Under such conditions astronomers were able to test part of Einstein’s now-celebrated general theory of relativity . That theory predicted that light from stars beyond the sun would bend from a straight path in a certain way as it passed the sun. The positions of stars photographed near the sun’s edge during a total eclipse on May 29, 1919, were compared with photographs of the same region of the sky taken at night; the results strongly supported Einstein’s theory. Our modern technology now allows astronomers to make most of the observations that once had to await an eclipse. But a total eclipse of the sun will always remain among the most impressive of natural spectacles and is a sight that will always be remembered.

Be sure to put it on your bucket list; you will not be disappointed. Additional resources

Question: What is the halo around an eclipse called?
Answer: Corona